Solid Waste Management Program

St. Louis Demolition Landfill Methane Information

History
St. Louis Demolition Landfill was permitted in 1981 under permit number 0218911. The landfill is approximately 45 acres. The facility is owned by the City of St. Louis (city).  The landfill ceased accepting waste in 1998. Because the facility operated in the 80s and 90s, regulatory requirements were not as stringent, and the site was not required to install gas monitoring wells as required of other landfills built after 1995. When the landfill closed in 1998, the city focused efforts on trying to complete closure of the site.    

Methane Migration and Monitoring Wells
During monitoring conducted on a property adjacent to the landfill in early 2008, methane gas was detected in a groundwater monitoring well. The department and the city discussed monitoring to determine whether or not methane gas was leaving the landfill and migrating off-site. The department received a methane gas monitoring plan from the city on May 29, 2009, and approved the plan on Sep. 1, 2009. The city installed two gas monitoring wells along the west side of the landfill on Oct. 5, 2009 with the intent to install additional wells by December. Methane gas was detected above the regulatory limit in one well, and the department asked the city to notify property owners located within 1000 feet of the well about the potential for methane gas to migrate off-site. The city conducted a public meeting on Oct. 21, 2009 to explain the methane migration to the nearby residents and advised the residents that they had completed installation of additional monitoring wells on the same day. The city also installed methane detectors in homes of nearby residents. Methane gas was detected in several wells in concentrations over the regulatory limit, and the department issued a notice of violation to the city on Nov. 23, 2009. In response to the department’s request to address the methane migration, the city submitted a corrective action plan on Nov. 30, 2009, which was denied by the department in January 2010, then revised and re-submitted by the city in February. The department approved the city’s revised gas investigation/corrective action plan on April 7, 2010.

Summary of Corrective Actions at Site
The city completed installation of a passive gas interceptor and venting trench approximately 1,200 feet long in September 2010. However, methane concentrations in the monitoring wells on and off-site continued to exceed the regulatory limit. In October 2010, the city asked to investigate the source of methane in one well, and in November the department agreed to allow the city to purge the well and observe concentrations in the well for three months. The city observed the methane concentrations and submitted a report to the department on April 12, 2011 with results of the observations. Due to continuing elevated concentrations of methane in the monitoring wells, the department required the city to submit a corrective action plan to address the methane migration. The city submitted a corrective action plan on Oct. 25, 2011, and the proposal was similar in nature to corrective actions taken in 2010, which was to purge the wells and see if the methane accumulated into the wells over time. Since this was not a corrective action to address future migration, but would just temporarily reduce concentrations in the wells, the department denied the proposal.

Over several months’ time, the city and the department could not come to an agreement to correct the elevated methane concentrations. Although concentrations of methane in the wells slowly decreased throughout the fall of 2011 and spring 2012, concentrations rebounded and occurred in different wells in the summer and fall of 2012. Due to the continued methane migration, the department issued a second notice of violation on Nov. 28, 2012. The city responded with the submittal of a landfill gas corrective action plan which the department received on Nov. 29, 2012.

The city continued to monitor methane concentrations in the well and documented a return to compliance with in methane concentrations during monitoring conducted in January 2013. Throughout 2013, the department and the city corresponded concerning corrective actions to prevent future elevated concentrations of methane in the monitoring wells. In November 2013, the department conducted monitoring in the methane monitoring wells and found elevated methane in one well located off-site. The department requested additional information from the city concerning the corrective action plan, but subsequently denied the proposal.

The department conducted gas monitoring on March 6, 2014 and found the concentrations of methane were within the regulatory limits. Discussions and negotiations with the city failed after the monitoring event and the department issued a notice of violation to the city on April 18, 2014 to document the elevated methane concentrations observed in November 2013 and an unapproved modification made to the permitted landfill without department approval. In August 2014, the department asked the Attorney General’s Office to assist in negotiations with the city to decrease methane concentrations to below the regulatory limit and to ensure future development on the property protects the integrity of the landfill.

Landfill gas is a term for a mixture of gases generated during the decomposition of waste at a landfill and includes methane (CH4), carbon dioxide (CO2) and trace constituents of many other contaminants. The migration of methane from a landfill is a concern because methane is explosive within a certain range of concentrations (concentrations between 5 and 15 percent by volume). Methane is a colorless and odorless gas. Until the methane gas concentrations are controlled on the landfill property, the department encourages property owners or tenants to be aware of the potential for methane migration in the area. If a property owner receives a notification letter from a landfill, they are being sent the letter as a precautionary measure to ensure they are aware of the potential for landfill gas migration in the area. The department and the city of St. Louis are encouraging residents and business owners to use caution and call 911 if they smell gas or the St. Louis Fire department at 314-533-3406 if they have concerns with their methane detectors.

For More Information

Department of Natural Resources
Solid Waste Management Program
573-751-5401 or 800-361-4827
www.dnr.mo.gov/env/swmp/methane.htm